1. Field of the Invention
This invention relates to mobile digital devices and electronic accessories therefor, and more particularly to controlling and powering electronic accessories from mobile digital devices.
2. Description of the Related Art
Mobile phones have become ubiquitous. Part of the explanation for the explosive growth is the fact that there has been a tremendous upsurge in the availability of applications. Gaming and social networking applications abound side by side of serious applications to enhance productivity, view documents and so on. An equally interesting trend is the surge in mobile phone accessories. For a long time accessories were mostly in extending the audio capabilities. Headphones of various kinds and noise cancelling headphones became mainstream products. Health monitoring devices such as blood pressure cuffs and credit card readers are other examples. Bluetooth brought about a proliferation of tiny, wireless audio accessories. Email focused keyboard accessories found their way to the market to overcome the tightly spaced, cramped keypads on the mobile phone. As mobile phones became more computationally more powerful and sported high quality displays, the accessories have also evolved. A number of accessories and applications have been developed for the iOS platform that covers the iPhone, iTouch and iPad device types.
Health and fitness has become a ripe area as evidenced by the following examples.
The Nike+iPod Sports Kit is a device which measures and records the distance and pace of a walk or run; Nike+ iPod, Wikipedia article http://en.wikipedia.org/wiki/Nike%2BiPod. It has a small transmitter device attached to or embedded in a shoe, which communicates with either the Nike+ Sportband, a receiver plugged into an iPod Nano, or directly with a 2nd, 3rd, or 4th Generation iPod Touch, iPhone 3GS or iPhone 4 or a Nike+Sportwatch. If using the iPod or the iPhone 3GS, iTunes software can be used to view the walk or run history. The kit includes two pieces: a piezoelectric sensor with a Nordic Semiconductor nRF2402 transmitter that is mounted under the inner sole of the shoe and a receiver that connects to the iPod. They communicate using a 2.4 GHz wireless radio. As the sensor battery cannot be replaced, a new one must be purchased every time the battery runs out.
You can check your blood pressure using an iOS device such as the iPhone, iTouch or iPad. Two market available devices are the iHealth BP3 (iHealth BP3 Blood Pressure Monitor, http://www.ihealth99.com/ihealth/bp3.html) and the Withings Blood Pressure Monitor (Withings Blood Pressure Monitor, http://www.withings.com/en/bloodpressuremonitor). Operation is extremely easy and requires download of an app onto the iOS device, put on a blood pressure cuff, tap the touchscreen to start the measurement, and within seconds you have a blood pressure reading that you can track every day.
Other examples in the health and fitness area are the FitBit (Fitbit, http://www.fitbit.com/product) and the Jawbone Up (Jawbone Up, http://jawbone.com/up).
Examples in the entertainment section include remote controllers for stereo equipment.
Musical instruments are another category. The Piano Apprentice product is a piano teaching tool for iPad, iPod and iPhone; see Piano Apprentice, http://www.ionaudio.com/products/details/piano-apprentice. It is a lightweight, portable 25-note keyboard with built-in stereo speakers that deliver piano sound in response to touch. It is a simple connection to the iPad, iPod or iPhone, download the free app, and start playing piano.
Another example of an accessory is the work of Jiang Li, a NASA scientist who created a 30-pin accessory that allows an iPhone or iPod touch to be used as a chemical sensor; see “NASA Ames Scientist Develops Cell Phone Chemical Sensor”, 10.30.09, http://www.nasa.gov/centers/ames/news/features/2009/cell_phone_sensors.html. The postage stamp-sized device packs 16 nanosensors that allow for detection and identification of low concentrations airborne ammonia, chlorine gas, and methane. Connected to an iPhone or iPod touch's Dock port and used with a special app, the system can send detection data to another device over a cellular or Wi-Fi network.
Many of the available mobile phone accessories are battery operated. Communication between the mobile phone and the accessory takes place over standard interfaces such as the wireless Bluetooth or over wired connections such as USB. It is not an ideal because it requires periodic replacement of the battery and in some cases user aggravation because of untimely replacements.
The IPHONE® mobile digital device available from Apple Computer Inc. of Cupertino, Calif., USA, allows limited access to the mobile phone's internal battery and communications through a proprietary connector. Accessories designed specifically with this family of mobile digital devices are designed to work with this proprietary connector. This controlled proprietary interface allows a limited amount of power to be drawn from the mobile digital device and also obtains bi-directional communication capabilities. The two drawbacks of this approach are that accessories have to be purpose built for these proprietary interfaces and often require a royalty payment.
Power and communications for accessories has been achieved using the headset audio port of the mobile phone. An interface of this type using a 3.5mm, 4 connector audio port is disclosed in Ye-Sheng Kuo et al., “Hijacking Power and Bandwidth from the Mobile Phone's Audio Interface,” ACM DEV'10: Proceedings of the First ACM Symposium on Computing for Development, December 2010. Kuo et al. use the right audio channel to provide a signal for power harvesting purposes, and the left audio channel and the microphone channel for bi-directional communications.